This invention generally relates to the installation of fasteners, including blind fasteners, and anchoring devices such as rivetless nut plates, which are used in manufacturing, maintenance and repair of aircraft, as well as in countless commercial applications. Such fasteners are installed by placing the fastener into an opening extending through the piece or pieces to be fastened and then applying a load to a male member, known as the break stem, which is initially attached to the fastener. The break stem shears from the fastener body at the end of the installation process upon the application of a predetermined tensile load by an installation tool.
The invention more specifically relates to fasteners used in confined areas which are usually installed using offset installation equipment. While the idea of offset installation is not new, decreases in the available space for installation results in a concomitant increase in the need for reduced sizing of the installation tool. This increased need has resulted in an increased demand for more compact offset and right-angle pulling heads for operation at concurrently increasing loads.
Examples of areas which present difficulties in installing fasteners include those which are close to other structures or to an edge, structure obstructed access, and blind access areas, as in the case of an fastener installed in a C-channel. Standard straight pulling head tools are usually unable to install fasteners in such applications.
Under known practices, pulling heads, including their nose assemblies, are typically custom designed to install fasteners of specific types and sizes. As construction of an aircraft requires the use of hundreds of types and sizes of fasteners, the procurement and use of the corresponding pulling heads can become expensive, unnecessarily complicating the logistics of production and procurement.
By way of background for pulling heads, U.S. Pat. Nos. 4,796,455 and 6,739,170 B1, both by Rosier, disclose offset nose assemblies, which because of the compact nature and configuration of the nose assembly, increase the applications where use of pulling heads is feasible. However, the devices disclosed by Rosier are dedicated to a single type and size of fastener and are not capable of being reconfigured. As a result, nose assemblies for uncommon types or sizes of fasteners are either unavailable or only available at an increased expense and a longer order lead time than for the more common fasteners. Additionally, because pulling heads tend to jam during operation and prolonged use only exacerbates this tendency, the currently known pulling heads have a relatively short life cycle, as when the active areas of a tool wear out, such that the tool has to be disposed.